Chap. XX. TEMPERATURE. 419 



then vibrated sometimes for thirty seconds. This I 

 observed in the prismatic comjDass, the only instru- 

 ment I had. 



The temperature of the countries I have ex- 

 plored, though situated near or under the equator, 

 is not so high as that of several countries further 

 removed from it, but I must say beforehand that I 

 am unable to judge of the temperature of the furthest 

 countries that I visited, for I was not there in the 

 hot season ; and I have no doubt that the heat is 

 sometimes still greater there than what I have ob- 

 served, as it was greater at Mayolo than on the sea- 

 shore. It has been noticed long ago that the tem- 

 perature of countries situated under the same degree 

 of latitude varies considerably. The extent of the 

 sea, deserts, the prevailing winds, the gulf stream, 

 the elevation of continents, &c., have a powerful 

 influence. So Africa, under the equator from west 

 to east, may have different temperatures, according 

 to its physical features. 



In Western Equatorial Africa, the great moisture 

 of the country and the vast forests are, no doubt, the 

 causes of the heat not being so great, the immense 

 jungle absorbing the heat radiated by the sun. The 

 hottest months of the year are December, January, 

 February, March, and April. In May, the tem- 

 perature begins to decrease ; in June it begins to be 

 cool, and July and August are the coldest. Then as 

 the rains commence to make their appearance, the 

 heat begins to increase. 



The same periodical changes of temperature, as far 

 as I have been able to judge, apply to the coast and 



2 E 2 



